1. Field of the Invention:
The present invention relates to a torque sensor for detecting the torque transmitted from a driving shaft to a driven shaft. The torque sensor can be used with the steering system of an automobile, for example.
2. Discussion of the Prior Art:
A mechanism for actuating values which control a conventional power steering system is disclosed, for example, in U.S. Pat. No. 2,964,017 issued to Howard E. Hruska. This known mechanism is not a torque sensor but is unique in structure. Specifically, as shown in FIG. 1, a slide cylinder 53 on a driving shaft 51 is coupled by springs 55 to a fixed sleeve 54 on a driven shaft 52. Rotation of the driving shaft 51 causes the slide cylinder 53 to move axially. The axial movement of the cylinder 53 is transmitted to a spool (not shown).
In this known mechanism, when the steering wheel is in its neutral position, the springs 55 are inclined at 45 degrees to the axis of the shafts. As the driving shaft 51 is rotated, the angle formed between each spring and the axis is increased or reduced. Therefore, the distance that the slide cylinder 53 moves axially as the driving shaft 51 rotates through a given angle varies, depending on the former angle. As a result, the amount of the axial movement of the slide cylinder changes, depending on whether the steering wheel is rotated clockwise or counterclockwise even if the driving shaft is rotated through a given angle. Thus, where this mechanism is applied to a torque sensor, the detected torque value varies according to the direction of rotation of the driving shaft if the same torque acts on the driving shaft.